Bimetallic circuit breaker



y 1948. w. F. EMIGH 2,440,937

BIHETALLIC CIRCUIT BREAKER Filed July 11, 19%

Inventar:

Wi lard F Emigh,

by HIS Attorney.

Patented 4, .1948

UNITED STATES PATENT OFFICE BIMETALLIC CIRCUIT BREAKER Willard F. Emlgh. Rldley Park, Pa., assignor to General Electric Company, a corporation of New York 9 Claims. 1

My invention relates to improvements in electric switches and more particularly to improvements in circuit breakers and especially circuit breakers the opening of which is effected both manually and by thermally responsive means.

Thermally responsive manually operable circuit breakers with which I am familiar are too bulky, too complicated or too costly to be used in place of fuses, for example, on house wiring circuits. Nevertheless, suitable, inexpensive, simple, reliable and foolproof circuit breakers for such service would ellminate the necessity of keeping a supply of fuses for replacements and would not only simplify restoration of service but would also place such restoration on a less hazardous basis.

An object of my invention is to provide an improved combined manually operable and thermally responsive circuit breaker which is relatively simple and compact. Another object of my invention is to provide a coactive form of manual and thermally responsive circuit breaker which has a. minimum number of parts and yet is prac tically foolproof in operation. A further object of my invention is to provide unimproved thermally responsive circuit breaker which is reliable in service and economical in cost and operation. These and other objects. of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide an electric switch comprising a circuit controlling member having a curved bimetallic supporting portionpivotally mounting one end thereof. Cooperating with this circuit controlling member is a' contact mounted for engagement by the member. Further, I provide means for moving the circuit controlling member into engagement with the contact. This means comprises an actuator which is movable in the circuit closing direction to flex the bimetallic portion of the circuit controlling member in'a direction transverse its curvature and is moreover arranged to release the member for circuit opening movement in accordance with, the stress on the bimetallic portion after engagement of the circuit controlling member with the contact. Further, in order to maintain the switch in the closed position, I provide means including a movable stop or catch engageable bythe circuit controlling member after the release thereof to prevent movement in accordance with the bias of the bimetallic portion thereof and thereby hold the member in engage arranged to be disengaged automatically upon temperature responsive movement of the bimetallic portion.

My invention will be better understood from the followin description when considered in connection with the accompanying sheet of drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a side elevation showing the open circuit position of a circuit breaker embodying my invention; Fig. 2 is a front elevation of the circuit breaker shown in Fig'. 1; Fig. 3 is a side elevation similar to Fig. 1 showing the circuit breaker in the circuit closed but not latched position, and Fig. 4 is aview similar to Fig. 1 showing the circuit breaker in the latched closed position with the tripped position indicated by the dotted lines.

In the illustrated embodiment of my invention, I have shovm a thermally responsive circuit breaker comprising a circuit controlling member 0 having an integral bimetallic supporting portion '2. one end of which is secured to a suitable base suchas a terminal 3 so as to flexibly mount the member i. As shown, the bimetallic portion or element 2 is curved substantially in the form of a semicircle, although my invention is not so limited, and is so constructed that upon heating its curvature is increased. In other words, the upper end of the bimetallic element moves toward the lower fixed end upon heating. As far as my invention is concerned, the circuit controlling member i may be rigid. Preferably, however, it is somewhat flexible for reasons hereinafter to appear. For cooperating with the circuit controlling member i to close a circuit, I provide a relatively stationary contact t which is mounted for engagement by the circuit controlling member i, a suitable cooperating contact 5 being mounted thereon.

In accordance with my invention, I provide means having a. cumming action for moving the circuit' controlling member 9 into engagement with the contact 3. As shown, this means comprises an actuator 8 manually movable in the circuit closing direction, clockwise as viewed in Figs. 1, 3 and 4, to stress the bimetallic element 2 in a direction to change its curvature from the normal curvature shown in Fig. 1 to the curvature shown in Fig. 3, for example. For this purpose, the actuator t is shown as mounted on a shaft 1 for movement therewith about an axis spaced from the circuit controlling member 2 on the side thereof corresponding to the concave side of the bimetallic element 2. As shown in Fig. 2, the shaft 1 is suitably supported on a bearing element 8 and may be turned .by any suitable means such. for example, as an insulated handle, not shown. but suitably arranged for rotating the actuator 6, as will be obvious to those skilled in the art.

For moving the circuit controlling member I to the closed circuit position upon clockwise movement of the actuator 8, the actuator is provided with a projection such as a pin 9 which, upon clockwise movement of the actuator, is engageable with and slides like a cam along the concave curve of the side of the circuit controlling member corresponding to the concave side of the bimetallic element 2 to move the circuit controlling member into engagement with the contact 4 and then further flexes the bimetallic element by efiecting a substantial lateral displacement of the upper end thereof in a direction to deform its normal curvature as shown in Fig. 3 and thereby produce a maximum contact closing pressure. Also in the illustrated embodiment of m invention, the circuit controlling member I is flexed only slightly upon movement of the actuator 6 in the circuit closing direction.

For releasing the circuit controlling member i from the actuator to partially reduce the maximum circuit closing stress on the bimetallic element 2 and the circuit controlling member I after movement to the circuit closing position, I provide the circuit controlling member (1 with an opening or slot in near the upper end or the bimetallic element 2 to permit passage of the pin 9 from one side of the circuit controlling member to the other. In order to hold the circuit controlling member I under normal pressure in the closed circuit position after the pin 9 has passed through the opening it, I provide suitable means on the actuator 6 such as a projection or movable stop I I which is engageable by the upper end of the bimetallic element 2 upon the release thereof to hold the circuit controlling member in engagement with the contact I as shown in full lines in Fig, 4. For limiting the clockwise rotation of the actuator so as to maintain the holding projection or catch II in the holding position, I provide a fixed stop 82. r

In order to return the actuator to the initial operating position shown'in Fig. l for closing the circuit breaker after an opening thereof. 1 provide a second or upper opening or slot to lo= cated slightly above the path of pin a but through which the pin 9 can pass from one side 01' the circuit controlling member to the other upon counterclockwise movement of the actuator t. During counterclockwise movement oi the actuas the flange I4 against which the Junction of the circuit controlling member I and the bimetallic element 2 abuts upon release from the catch II. As is customary in the circuit breaker art. the parts will be mounted on an insulating base, not shown.

Assuming the parts positioned in the circuit open position as shown in Fig. l and that it is desired to dose the circuit' breaker, then the actuator 6 is turned clockwise approximately 90 to the position shown in Fig. 3 where the pin 5 is just about ready to pass through the opening it in the circuit controlling member. During this movement of the actuator 6, the contacts d and 5 have been brought into engagement. the circuit controlling member I has been stressed and the curvature of the bimetallic element 2- has been materially deformed so as toproduce the maximum circuit closing pressure. Upon further clockwise movement of the actuator 6. until engagement with the stop I2, the pin a passes through the opening it to the other side of the circuit controlling member thereby releasing the maximum stress on the circuit controlling member i and the bimetallic element 2. In consequence of this release in stress, the bimetallic element springs back slightly into engagement with thecatch ii and the contacts l and 5 are held in the closed circuit position under normal pressure as indicated in full lines in Fig.4.

If now current flow through the bimetallic element 2 and the circuit controlling member I ator 6 from the position shown in Fig. 4, the

pin 9 will ride more or less free of the circuit controlling member I on the convexside thereof corresponding to the convex side 01 the bimetallic element until the convex side of the circuit controlling member adjacent the opening I3 is engaged by pin 9. Thus a camming action is produced that tends to compress the semicircular bimetallic portion 2 suihciently to lower the opening I3 into the path of pin 9 and thereby efiect passage of the pin therethrough. After passage of the pin 9, the bimetal portion at once expands so as again to raise the opening 13 to its normal position slightly above the path of pin 8.

In order to prevent rebound or the movable contact 5 into engagement with the relatively stationary contact [during manual opening operation of the circuit breaker because of the resilience of the bimetallic element 2. the actuis sumcient to produce a temperature responsive movement of the bimetallic element to the position shown by the dotted lines in Fig. 4, the catch ii is disengaged automatically and thus is no longer able to maintain the circuit breaker in the closed position. Consequently, when the stress of the bimetallic element 2 is fully released the circuit controlling member i takes the position indicated by the dotted'lines in Fig, 4.. It now it is desired to reclose the circuit breaker, then the actuator 6 is turned counterclockwise substantially during which operation the pin 9 passes through the opening it to the rear of the circuit controlling member and, upon cooling of the bimetallic element 2, the circuit con= trolling member takes up the normal open position shown in Fig. 1 wherein the passage 88 is located in its normal position slightly above the path of pin Q.

If it is desired at any time to open the circuit breaker independently of the bimetallic element. the actuator o is turned counterclockwise. During this movement. the pin 9 rides along the front face of the circuit controlling member l and the catch l i is disengaged from the bimetah lic element 2. Near the end of the counterclockwise movement of the actuator 8, the pin 9 passes through the opening is to the rear of the circuit controlling member I, and the parts are again positioned as shown in Fig. 1.

While I have shown and described my invention in considerable detail. I do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the truespirit' arid scope oi my invention.

What I claim as new and desire to secure'by Letters Patent of the United States is:

1. An electric switch comprising a'circuit controlling member having a curved bimetallic portion flexibly mounting one end thereof, a 'contact mounted for engagement by said circuit conmember in engagementwlth saidgcontact and for disengagement upon a predetermined. temperature responsive movement of said curved bimetallic portion.

2. An electric switch. comprising a curved bimetallic element supported adjacent one end to eifect a predetermined relative movement of the other end thereof upon heating, a circuit controlling member carried by the other endof said bimetallic element, a contact mounted for engagement by saidcircuit. controlling member, means for moving said. circuit controllingmembar into engagement with said contact compris- 3. An electric switch comprising a substan-.

tially semicircular bimetallic current conducting element rigidly supported adjacent one end to eilect apredetermined relative movement of the other end thereof upon heating of said element, a curved circuit controlling member carried by said bimetallic element adjacent the other end thereof, a'stationary contact -mounted for engagement by said circuit controlling member, means for moving said circuit controlling member into engagement with said contact comprising a pivotally mounted actuator movable in the circuit closing direction to engage the circuit controlling member and stress the bimetallic element in a direction transverse its curvature and subsequently release the circuit controlling member to reduce the stress on the circuit controlling member and the bimetallic element after engagement of the circuit controlling member with the contact, and means including a stop on said actuator engageable by the bimetallic element after the stress relief thereof to hold the circuit controlling member in engagement with said contact and disengageable by the bimetallic element upon heating thereof.

4. An electric switch comprising a curved bimetallic element supported adjacent one end to cliect a predetermined temperature responsive curvature thereof, a correspondingly curved circuit controlling member carried by the other end of said bimetallic element, a stationary contact mounted for engagement by saidclrcuit controlling member, an actuator mounted for movement about an axis spaced from said member on the side thereof corresponding to the concave sideof said bimetallic element, a projection on said actuator engageable upon movement thereof in one direction with said circuit controlling member to efiect movement thereof into engagement with said contact and upon further movement to flex said bimetallic element in a direction transverse its curvature, said circuit controlling member being provided with an opening through which said projection passes upon said further movement thereof to release the member and the bimetallic element after the member engages the contact, and a catch on said actuator engagcable by said bimetallic element after the release thereof to hold said circuit controlling member in engagement with said contact and disengageable by said bimetallic element upon said predetermined temperature responsive curvature thereof.

5. An electric switch comprising a curved bimetallic element rigidly supported adjacent one I end to ciiect temperature responsive curvature thereof, a correspondingly curved circuit controlling member having one end secured to the other end of said bimetallic element, a stationary contact mounted for engagement by said circuit controlling member, an actuator mounted for movement about an axis spaced from said circuit controlling member on the side thereof corresponding to the concave side of the bimetallic element, a projection on said actuator engageable with the side of the circuit controlling member corresponding .to the concave side of the bimetallic element upon rotation of the actuator in one direction to move the member into engagement with saldcontact and to flex said bimetallic memher in a direction transverse its normal curvature, said circuit controlling member being provided with an opening near the end adjacent the bimetallic element through which said projection passes to release the bimetallic element, and a catch on said actuator engageable by said bimetallic element upon the release thereof to hold said circuit controlling member in engagement with said contact and disengageable by said bimetallic element upon said temperature responsive curvature thereof.

6. An electric switch comprising a semicircular bimetallic element rigidly supported adjacent one end to eifect a predetermined temperature responsive movement of the other end thereof, a curved circuit controlling member secured to said bimetallic element adjacent the other end thereof and provided with two spaced openings, 9. stationary contact mounted for engagement by said circuit controlling member, an actuator mounted for movement about an axis spaced from said circuit controlling member on the side thereof corresponding to the concave side of said himetallic element, a projection on said actuator engageable upon movement thereof in one direction to slide along said side of said circuit controlling member to effect movement thereof into engagement with said contact and to flex said bimetallic element in a direction transverse its curvature and after a predetermined further movement of the actuator to pass through one of the openings in the circuit controlling member to the other side thereof whereby to release the member and the bimetallic element, and r catch on said actuator engageable by said bimetallic element after the release thereof to hold said circuit controlling member in engagement with said contact and disengageable by said bimetallic element upon said temperature responsive movement of the other end thereof, the pro metallic element rigidly supported adjacent one end to effect a predetermined temperature r'esponsive curvature thereof, a curved circuit controlling member secured to said bimetallic element and provided with two spaced openings, a contact mounted for engagement by said circuit controlling member, an actuator mounted for movement about an axis spaced from said circuit controlling member on the side thereof corresponding to the concave side of said bimetallic element, a projection on said actuator engageable upon movement thereof in one direction to slide along said side of said circuit controlling member to effect movement thereof into engagement with said contact and to flex said bimetallic element in a direction transverse its curvature and after a predetermined further movement of the actuator to pass through one of the openings in the circuit controlling member to the other side thereof whereby to release the member and the bimetallic element, and a catch on said actuator engageable by said himetallic element after the release thereof to hold said circuit controlling member in engagement with said contact and disengageable by said himetallic element upon said predetermined temperature responsive curvature thereof, the projection on said actuator upon a reverse movement thereof moving along said other side of said circuit controlling member and passing through the other opening therein to the opposite side of the member.

8. An electric switch comprising a curved bimetallic element rigidly supported at one end to thereof corresponding to the concave side of the bimetallic element, a projection on said actuator engageable with the side of the circuit controlling member corresponding to the concave side of the bimetallic element upon rotation of the actuator in one direction to move the circuit controlling member into engagement with said contact and to flex said bimetallic element in a direction transverse its normal curvature. said circuit controlling member being provided with an opening near the end adjacent the bimetallic element through which said projection passes to release the circuit controlling member for movement in accordance with the stress on the bimetallic element, and a catch on said actuator engag'eable by said bimetallic element upon the release ofsai'd member to hold said circuit controlling member in engagement with said contact and disengageable by said'bimetallic element upon said temperature responsive movement of the other end thereof, and said circuit controlling member being so shaped that upon movement of the actuator in the reverse direction to release said catch said projection engages the side of the member-corresponding to the convex side of the bimetallic element and moves the member to insure separation thereof from said contact, said projection subsequently passing to the other side of the member through an opening provided therein near the free end of the member.

-9. 'A thermally responsive switch'comprising a movable circuit-controlling member having a normally curved current-conducting bimetallic supporting portion flexibly mounting one end thereof, a'contact mounted for engagement by said circuit-controlling member, means including a pivoted actuator having a limited angular movement for flexing said curved supporting portion to engage said circuit-controlling member with said contact and a further-angularmovement for releasing'said member, and means including a movable stop carried by said actuator intoposition for engagement by said circuit-controlling member upon said release thereof to hold the member in engagement with said contact and tor disengagement upon a predetermined temperature responsive movement of said bimetallic portion. WILLARD F. EMIGH.

nananniscas crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS 

